Thermionic valve



May 16, '1933'. J. RoBlNsoN THERMIONIC VALVE Filed July 6, 1927 deffejoPatented May 16, 1933 UNITED STATES JAMES ROBINSON, F LONDON, ENGLANDTHERMIONIC VALVE Application filed July 6,1927, Serial No.' 203,

This invention relates to thermionic valves having a. single cathode orlament, one or more control electrodes or grids and one or more plateelectrodes or anodes.

According to the invention such valves are provided inside theirenvelopes with additional juxtaposed elements of similar physicalcharacter to the anode or grid, which are herein called grid elementsand anode elements because one or other of these elements, but not bothofthem, may be an extension of or directly connected with the grid oranode of the valve, and such connection is the only permanent connectionwithin the -valve between these additional elements and any of the valveelements. Fur ther, these elements are, by means other than screening,placed effectively or substantially outside the cathode field, that isto say there is no flow or comparatively little iow of electrons fromthe filament through the grid elementto the anode element, with theresultvthat these juxtaposed elements fulfill only `one of the functionsAof a valve grid L' and anode, viz. by their capacity they allow highfrequency Veffects to pass between the anode and the grid circuits. Whenthe anode element or the grid element'is an extension of the valve anodeor grid respectively, only that part of the element which is outside theelectron stream constitutes the anode element or the gridelement, as thecase may be', in the sense in which these terms are herein used.

These additional grid and anode elements are of the same` physicalcharacter as the grid or anode of the valve, that -isto say they haveextended metallicA surfaces which in their juxtaposed positionconstitute a cons 40 denser having a capacity of the saine order as thegrid-anode capacity of the valve, and when it is desired to have thesecapacities exactly equal, the additional grid and anode elements aremade physical duplicates of the valve grid and anode.

Such thermionic valves in one form or another are of utility as currentamplifiers or as frequency multipliers, or for balancing outdisturbances due to irregularities or changes of emission such as areobtained 783, and in Great Britain November 30, 1926.

when the filament is heated by alternating current. In the latter casethe extra anode and extra grid, if employed, need notl be used for thehigh frequency or low frequency wirelesseii'ects, but will be used to 55obtain an anode current which varies with theemisslion from thefilament. This varying anode current in the second anode can n ow beemployed to counteract variations y of anode current from the firstanode;v or again, it may be used to vary the potential of the 0rid so asto keep the anode current in the rst anode independent of variations ofemission.

The subdivision and arrangement of thefl5 elements of the various typesof valves contemplated are ,illustrated diagrammatically in Figs. l to 4ofthe accompanying drawing, while Figs. 5 and 6 illustrate also diagram-Amatically two constructions of valves of the170 type'shown in Fig. l;Fig. 7 illustrates the applicatipn of sucha valve to nigh frequencyamplification; Fig. 8, a modified arrangement having the same object.

The valves shown in Fig. 7 have their 75 elements arranged in the mannershown in Fig. l, while the valve shown in Fig. 8y is of the kindillustrated in Fig. 2.

In the type of valve shown in Fig. 1, the anode is subdivided while thegrid is undivided. The two portions A, A of the anode may be identical,but are not necessarily so.

In Fig. 2 the grid is subdivided, while ,the anode is undivided. Asshown, the grid 85,

is divided into two portions G and G and these portions may be identicalin each case, or are unequal. The filament F may be asymmetricallydisposed with respect to the grid and anode. Y i

In Figs. 3 and 4 both the anodeand the grid are subdivided. Thesesubdivisions may be equal and` symmetrically disposed with respect toeachother, but are not necessarily so.

The anode portions may be cylindersv A,

lA placed end toend as shown in Fig. 5,

or side by side Yas shown in Fig. 6, and separated fromy each other sothat there is no direct electrical conduct-ion between thein,;10(E

and the lament F may be co-terminous with one cylinder, while thecoil-shaped grid G, which in Fig. 6 is shown as being in twoconductively connected parts, extends along the entire length of bothcylinders, which may be equal and symmetrically disposed with respect tothe grid. Instead of having a double or divided anode and a single grid,there may be a double or divided grid and two anodes or a single anodeextending along the length of both grids, the filament beingco-terminous with one grid only or with both.

Obviously more than one of such special valves can be combined in onecontainer. In this case the filaments can be arranged to'bc in seriesorin parallel; for example, a convenient unit is two such special valveelements and one ordinary three-electrode element to act as a rectifierinside one glass envelope.

Valves constructed in accordance with the present invention may beemployed, e. g., for vhigh frequency or low frequency emplification, andFig. 7 illustrates diagrammatically the use of two such valves fortwost-age high frequency amplication.

As shown, capacity coupling is used between the two valves, butinductive coupling can be substituted. It will be seen that the twoportions of the anode A, A in each of the valves V, V `are connectedwith the ends of the anode inductance coil I, which is preferably tunedby a shunting condenser C. Preferably also the high tension battery isconnected with the divided anodethrough a central or variable tappingpoint X on the anode inductancecoil I. In this case it will be notedthat only one portion of lthe anode, namely A, is in the effective fieldof the-gridv and filament, the latter being coterminous with the anodeA. v y Fig. 8 shows diagrammatically a construction of valve in whichthe grid is divided into two parts Gr, G', while'` the anode A which isco-extensive withthe two grids is undivided, the filament Fbeingco-terminus with one part of the divided grid, namely part G. Thetwo parts'of the divided grid are connected ldirectly with the 'ends ofthe gridcoil K which is tuned by means of variable condenser O shuntingthe ends of the grid coil. A tapping Y (which 'may be central oradjustable) on the grid coil K is joinedvtofilament F through anypotential device required,'as for example a battery and potentiometer.

These special valves may be combined for different purposes in variousways with each other, or with ordinary three-electrode valves. 'Forinstance, three valves such as shown in Fig-8 may be used forthree-stage lhigh frequency amplification followed by an ordinary'three-electrode valve acting as 'a detector vand oscillator, that is' tosay this of: carrying the same into practical effect,

I claim j 1. A thermionic valve having a single filament, a controlelectrode and plate electrode and a plurality of additional juxtaposedelements of similar physical character to the said f electrodes anddisposed substantially outside the cathode field, the filamenty beingasymmetrically disposed with respect to the valve electrodes and ltheadditional juxtaposed elements.

2.' A thermionic value according to claim l, whereinA the additionaljuxtaposed ele- Vments have substantially the same reactance to highfrequency currents as the grid anode capacity ofthe valve.'

3. A thermionic valve having a single filament, wherein besides thecontrol and plate electrodes of the valve there are provided inside theenvelope additional juxtaposed elements of similar lphysical characterto the said electrodes of the valve, one-of which additional elements,but not both, being directly connected with one of the said electrodesof the valves, such connection being the only permanent connectionywithin the valve between these additional elements and any of the valveelectrodes and these additional elements being located substantiallyoutside the cathode eld.

4. A thermionic valve according to claim l, wherein theadditionaljuxtaposed elements are placed effectively outside the cathodefield by an appropriate asymmetrical disposition of the cathode withrespect to the valve elements and. the additional juxtaposed elements.

In witness whereof I have signed my name to this specification.

JAMES ROBINSON.

